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Dr. Bob is Robert Hsiung, MD,
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Posted by psychobot5000 on June 5, 2007, at 13:29:39
http://www.medicalnewstoday.com/medicalnews.php?newsid=72033
This is a report on 4 largish studies, showing positive results for guanfacine XR in ADHD. The studies are in children and adolescents, but I'd imagine they are relevant to adults with cognitive difficulties as well.
I think the results reinforce the notion that guanfacine/Tenex can be a useful adjunct for depressive people who have cognitive problems. In any case, it's good to have this scientific confirmation for the common practice of prescribing guanfacine for ADD. I would imagine that these Phase III trials would mean that guanfacine XR will be formally approved for an ADHD indication.
Best,
Psychbot
Posted by linkadge on June 5, 2007, at 21:05:40
In reply to Guanfacine XR Significantly Improved ADHD Symptoms, posted by psychobot5000 on June 5, 2007, at 13:29:39
interesting. Still doesn't resolve why a NRI could treat ADD and a drug like this that essentially lowers noradrenergic neurotransmission would also work.
Linkadge
Posted by psychobot5000 on June 5, 2007, at 22:59:01
In reply to Re: Guanfacine XR Significantly Improved ADHD Symptoms, posted by linkadge on June 5, 2007, at 21:05:40
> interesting. Still doesn't resolve why a NRI could treat ADD and a drug like this that essentially lowers noradrenergic neurotransmission would also work.
>
>
> LinkadgeStrange, isn't it? Researchers seem to be proposing that Guanfacine selectively acts on alpha-2a receptors, present in the brain and which help regulate some aspects of alertness and focus. Thus, while guanfacine lowers noradrenaline levels overall through its action on alpha 2 receptors, it also has some direct action on awareness that more than compensates. That's how I understand it, anyway.
I suppose this helps put it in the position of being useful for relieving anxiety (in some people who find stimulants exacerbate it) and boosting attention at the same time.
Psychbot
Posted by linkadge on June 6, 2007, at 6:33:11
In reply to Re: Guanfacine XR Significantly Improved ADHD Symp » linkadge, posted by psychobot5000 on June 5, 2007, at 22:59:01
I am guessing it was more effective for the hyperactive form than the innatentive form.
A number of animial models of ADHD involve hyperactivity of noradrenaline with respect to dopamine, esp in the frontal cortex.
Perhaps part of the drug effect is to alter this ratio?
Linkadge
Posted by psychobot5000 on June 6, 2007, at 12:22:05
In reply to Re: Guanfacine XR Significantly Improved ADHD Symp, posted by linkadge on June 6, 2007, at 6:33:11
> I am guessing it was more effective for the hyperactive form than the innatentive form.
>
> A number of animial models of ADHD involve hyperactivity of noradrenaline with respect to dopamine, esp in the frontal cortex.
>
> Perhaps part of the drug effect is to alter this ratio?
>
> LinkadgeHmm. That's interesting. I know that remeron increases noradrenaline, for example (in an action precisely opposite the alpha 2 agonists), and was counterproductive for my own ADHD-type symptoms. Of course that could have been its effects on H1, (or serotonin receptors), but for several reasons, I don't think this was the case. ...I guess I can see how extra NA might exacerbate hyperactivity (though doubtless this is a crude way of putting it).
I think docs have worked along that type of line of thought concerning guanfacine, but as far as I can tell, the studies seem to show real effects on inattention as well, sort of in contrast to conventional wisdom. I've seen some much smaller studies in which it seems to help memory and concentration very modestly (tests against placebo in reorganizing shapes to fit together, or something like that).
This may be in contrast to clonidine, though, which often doesn't get positive results for inattention. This could be explained by the unwanted action of blocking alpha-1 receptors, or also by its lack of selectivity for the alpha-2a subset.
But the DA/NA ratio you mention seems an interesting idea. Very few medications that increase dopamine do so without increasing NA as well, after all, and maybe they'd be more effective if they did. Certainly ought to have less effect on the heart and be less anxiogenic.
Psychbot5000
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